Plate bending machines

ABSTRACT

A plate bending machine particularly for heavy duty applications including a vertically disposed roll member rotatably disposed in a bipartite frame, one part of the frame being hinged to be moved away from the roll member. A pair of hydraulic power cylinders forming part of a movable bolster mounted in the other part of the frame, the bolster being reciprocable relative to the roll member and including plate contacting bolster abutments positioned one on each side of the roll member centre to bend a plate about the roll member. Sensing arrangements are included to ensure alignment of the bolster with the roll member. The bolster abutments are adjustable relative to the roll member centre to lessen the amount of &#39;&#39;&#39;&#39;end flat&#39;&#39;&#39;&#39; obtained on a bent workpiece. A hydraulic intensifier is also disclosed.

" States Hoggan et al.

tent 1 June 24, 1975 PLATE BENDlNG MACHINES [73] Assignee: Industrial Engineering Limited,

Australia 22 Filed: Oct. 15, 1973 21 Appl. No.: 406,614

Primary ExaminerMilton S. Mehr Attorney, Agent, or Firm-Wenderoth, Lind & Ponack [5 7] ABSTRACT A plate bending machine particularly for heavy duty applications including a vertically disposed roll member rotatably disposed in a bipartite frame, one part of the frame being hinged to be moved away from the roll member. A pair of hydraulic power cylinders forming part of a movable bolster mounted in the other part of the frame, the bolster being reciprocable relative to the roll member and including plate contacting bolster abutments positioned one on each side of the roll member centre to bend a plate about the roll member. Sensing arrangements are included to ensure alignment of the bolster with the roll member. The bolster abutments are adjustable relative to the roll member centre to lessen the amount of end flat obtained on a bent workpiece. A hydraulic intensifier is also disclosed.

4 Claims, 5 Drawing Figures PLATE BENDING MACHINES This invention relates to a vertical plate bending machine, particularly of the heavy duty type having a vertically disposed roll about which the plate is adapted to be bent, a stationary bolster including hydraulic cylinders secured and located thereto, a movable bolster actuated by said cylinders for reciprocating movement to and from said roll, a base plate for mounting the machine and a top plate mounted for hinged movement.

The provision of a stationary and moving bolster has previously been thought to be essential in order to maintain accuracy in the bending operation, which must be performed to close tolerances, and also to provide adequate strength for performing the operation.

It has since been surprisingly found that the construction of the machine can be greatly simplified without affecting the accuracy thereof but greatly reducing the cost of manufacture by omitting a stationary bolster.

Furthermore, when the end of the workpiece being bent is reached, the remaining end edge portion cannot be bent in existing machines known to applicants and accordingly, there is a small portion called an end flat" of the bent workpiece not curved. This end flat can be reduced in width by increasing the load on the bolster and reducing the distance between the forming bar and the centre of the roll member. As a result the yield bending moment as applied to the workpiece will be achieved over a shorter distance.

It is usual to locate the forming bars in vertical plate bending machines symmetrically about the roll centre line whereby each forming bar has half machine capacity.

Accordingly, it is an object of the present invention to provide an improved plate bending machine which is relatively simple in construction but extremely accu rate in operation.

It is a further objective of the present invention to lessen the end flat dimension without physically increasing the capacity of the machine, however, the effective machine capacity is increased without an increase in horsepower requirement.

According to one aspect of the present invention there is provided a plate bending machine comprising a roll member rotatably mounted at each end in a frame, hydraulic cylinder piston arrangements mounted relative to said frame, a movable bolster slidably mounted in said frame for movement towards said roll member in response to applied fluid pressure in said piston and cylinder arrangements, said bolster including abutment members for contacting a plate to be bent whereby the plate is conformed to the periphery of the roll member.

According to a further aspect of the present invention there is provided a plate bending machine comprising a roll member rotatably mounted at each end in a frame including a fixed part and a hinged part, the hinged part being detachably secured to an end of said roll member, hydraulic cylinder piston arrangements mounted relative to said frame parts, a movable bolster slidably mounted between said frame parts for movement towards said roll member in response to applied fluid pressure in said piston and cylinder arrangements, said bolster including abutment members for contacting a plate to be bent whereby the plate is conformed to the periphery of the roll member, the piston or cylinder being an integral part of said movable bolster.

Preferably, the frame is bipartite and each part is of open construction whose longitudinal axis taken on the line of movement of said bolster is substantially in alignment with the respective centre lines of said hydraulic cylinder and piston arrangements mounted on said frame. Preferably, the piston cylinder arrangements are mounted within the open section frame and abut a cross member of each part of the frame, the arrangement being such that the respective axes of the frame parts and hydraulic arrangements are substantially in alignment.

In a further aspect of the invention there is provided a plate bending machine including a bi-partite frame of open construction, a substantially vertical roll member connecting the frame members at top and bottom of the roll member, hydraulic cylinder piston arrangements mounted relative to said frame parts, a movable bolster slidably mounted and extending between said frame members for movement towards said roll memher in response to fluid pressure in said piston and cylinder arrangement, said bolster including abutment members for contacting a plate to be bent whereby the plate is conformed to the periphery of the roll member, the piston or cylinder being an integral part of said movable bolster, limit switches arranged relative to said frame members controlling flow of fluid to said piston cylinder arrangements so that the final curvature of a bent plate is determined and ensuring parallel alignment of the bolster member and said roll member at the completion of a bending stroke.

There is provided according to a further aspect of the present invention an improvement in a plate bending machine comprising a roll member mounted in a frame, a hydraulic piston and cylinder arrangement mounted in the frame, a movable bolster mounted in the frame for reciprocal movement relative to said roll member in response to fluid pressure in said piston cylinder arrangement, said bolster including abutment members for contacting a workpiece to be bent whereby the workpiece is conformed to the periphery of the roll member, the improvement including adjustable mounting means for said abutment members on said bolster whereby the distance between the centre line of the roll member and each abutment member is variable.

In a further aspect of the invention there is provided an hydraulic intensifier for use in hydraulic pressure circuits for increasing the effective pressure of fluid in a circuit comprising a fixed outer cylinder member and an inner cylinder member slidably, sealingly and concentrically arranged in said outer cylinder, a fixed seal member sealingly arranged in said inner cylinder, the inner cylinder being movable relative to said seal member, the outer cylinder adapted to communicate with said fluid circuit for inflow of pressurised fluid, and the inner cylinder adapted to communicate with said fluid circuit for outflow of fluid through said seal member at a greater pressure than the inflow fluid pressure. The intensifier is arranged for connection into the hydraulic circuit of the plate bending machine. The intensifier is switched into the pressure circuit only on occasions when additional hydraulic pressure is required.

The invention will be described in greater detail having reference to the accompanying drawings in which:

FIG. 1 is a side view of the plate bending machine,

FIG. 2 is a sectional plan view of the plate bending machine with the top of the machine removed,

FIG. 3 is a plan view of a machine showing the improvement according to the present invention,

FIG. 4 shows a pressure intensifier for hydraulic fluid according to the present invention, I

FIG. is a plan view of the machine with the abutment members arranged asymmetrically.

FIG. 3 shows part only of the plate bending machine. The machine is otherwise similar to the machine shown in FIGS. 1 to 2 referred to earlier.

Referring to FIGS. 1 and 2, a roll member 9 is desir ably vertically disposed in front portions 2a and 3a of a bi-partite frame comprising a bottom frame 2 and top frame 3, both of rectangular open construction. Hydraulic piston and cylinder members 5 and 6 are provided with each piston 5 secured to the back portions 2b, 3b of frames 2 and 3 respectively, as shown. The cylinders 6 are integrally secured to bolster member 1 for movement with the cylinder towards the roll member 9 upon application of fluid pressure to the pistoncylinder system. Thus, the roll member 9 and bolster member 1 effectively connect and secure the frames 2 and 3 together. As shown in FIGS. I and 2, bolster abutments 10 extend from bolster 1 toward the roll member 9. A plate 22 is simply fed into the nip between the vertical roll member 9 and the bolster abutments 10. Rollers 10c maintain contact with the plate 22 to hold the plate during feeding of the plate during rotation of the roll member 9. One of the frame parts 3, as shown in FIG. 1 is hinged at 4 relative to the piston 5 associated therewith, whereby the part can be rotated away from the bolster 1 and the roll member 9. Movement of the hinged part is preferably controlled by a light duty hydraulic piston and cylinder arrangement 11 connected to the fixed part of the two part frame. When the hinged part is in engagement with the roll member (as shown) the frame part 2, roll member 9 and bolster 1 form a rigid structure with the bolster 1 and cylinders 6 being reciprocable relative to the pistons 5 which are fixed relative to the frame cross members 2b and 3b. However, since the top and bottom frames are not connected by a fixed bolster but only by the roll member 9 and movable bolster 1, means designed to ensure accurate alignment at least at the completion ofa bending stroke are normally required.

Statically, the top and bottom frame members are rigidly connected together by the roll member and the movable bolster, as previously described. However dynamically the relationship between these members changes because movement of the bolster will immediately allow misalignment of the top and bottom frames, whereby the top frame may lead or lag the bottom frame during a plate bending stroke of the bolster. This misalignment can be simply detected as relative movement between the top and bottom frames and this relative movement can be utilised to correct for any misalignment that occurs.

Referring to FIG. 1, a mechanical lever 8 associated with a limit switch is provided for accurately sensing such relative movement between the frames. Bottom frame 2 is provided with an upstanding column 7. A lever 8 is mounted at the top of column 7 with its fulcrum 8a adjacent the top frame. A contact member is mounted on the top frame engaging the short side of the lever 8. It will be appreciated that the sensitivity of the device can be easily controlled by selecting a suitable lever length on each side of the fulcrum 8a.

A second limit switch 23 is provided on the bottom frame member 2 in association with contact member 24 mounted on the movable bolster 1 or cylinder 6 to control flow of fluid to the bottom cylinder and specifically to terminate fluid flow at the completion of a bending stroke.

In operation the lever 8 is adjusted so that the limit switch 20 is actuated whenever the top frame 3 is in parallel alignment with the bottom frame 2. At this point flow of fluid to the top cylinder is stopped. Thus,

in operation fluid is applied continuously to the bottom cylinder but is applied to the top cylinder only when the bottom frame 2 leads the top frame 3. Thus, the machine operates at all times with the top frame parallel with or lagging slightly behind the bottom frame.

At the completion of the stroke, limit switch 23 is actuated to stop fluid flow to the bottom cylinder. Thus, this switch 23 provides a control over the length of stroke of the bolster and therefore a control over the curvature of the bent plate.

Before the bending stroke is completed fluid is applied to the top cylinder until limit switch 20 is closed, at which time the bolster member is closely parallel with the roll member 9.

After a power stroke, fluid pressure in the bolster cylinders 6 is removed and the bolster 1 is returned to its starting position by known return means. Rollers 10c maintain contact with the plate to keep the plate in engagement with the roll member 9. After each bending stroke by the bolster the plate 22 is advanced by part rotation of the roller 9. The roller may be rotated by a self-locking worm and worm gear mechanism or similar known means (not shown). Alternatively, particularly in heavy duty applications, rotation of the roll member may be achieved by actuating a toothed rack 15 against a gear wheel 16 attached at an end of the roll member 9. Similarly, in order to ensure that the roll member does not rotate during a bending stroke a pivoted sector rack 15a is preferably provided to mesh with and lock the gear wheel 16 whilst the bolster is moving.

Accordingly, it will be appreciated that a plate bending machine of simplified construction is provided by the invention, yet it is suitable for heavy duty use. The hinge mechanism 4 for the hinged frame part is not required to carry any of the load imparted by the bolster and accordingly, its construction is economical.

Further embodiments of the invention will be described with reference to FIGS. 3 to 5 of the drawings. Referring to FIGS. 3 and 5, there is provided a roll member 9 in fixed position relative to bolster abutment members 10a and 10b. The roll member is mounted in a bipartite frame 2 in identical manner to that already described with reference to FIGS. 1 and 2. The abutments may be mounted on bolster 30 for independant movement in the direction of the arrows relative to the centre-line of the roll member. The bolster 30 is provided with serrated surfaces 31 for inter-engagement with similar surfaces on the abutments 10a and 10b. The abutments are held against surface 31 by compression springs 32 mounted in travelling housings 33. To relieve friction the housings are mounted on wheels 39. Springs 32 are associated with hydraulic cylinders 34 which are capable of overcoming the spring bias to move shaft 35 and thereby disengage the serrated surface 31 and loosen the abutments 10a and 10b, for lateral movement toward or from the roll member centreline.

The travelling housing 33 includes a threaded tube 37 for mounting on a lead screw 36 for movement upon turning of the lead screw. Simple means such as a square key 38 are provided for turning the screw shaft 36.

In operation, the abutment members may be positioned symmetrically about the roll member centreline for normal bending of the workpiece as shown in FIG. 3. However, to prevent formation of a large end flat one abutment member 1012 can be moved toward the roll member 9 and abutment member a can be moved away from the roll member described above and thus the effective force applied to the workpiece 22 is increased to provide the necessary bending moment on the plate. FIG. 5 shows the asymmetrical arrangement.

FIG. 4 shows an arrangement of a fluid pressure intensifier which is preferably incorporated in a plate bending machine.

As plate bending machines are invariably used to their maximum capacity for only a small percentage of their time it has been found economic to manufacture low capacity equipment for normal use, and to incorporate a hydraulic intensifier into the hydraulic fluid circuit to increase fluid pressure during the last stage of a working stroke during a bending operation without the requirement of added horsepower. The intensifier can also be fitted to existing hydraulic equipment for increasing the effective capacity thereof. Thus, the intensifier is preferably utilised only where additional pressure is required. Furthermore, the intensifier is switched into the circuit in the last stage of the working stroke of the bolster to increase the capacity of the bending machine.

Referring to FIG. 4, the mechanism includes an outer cylinder 40 with a hydraulic fluid inlet 41, an inner cylinder 42 slidably mounted within the outer cylinder and a fixed sealing member 43 mounted within the inner cylinder. Both cylinders are provided with seals 44, 45. Fluid duct 46 is provided in the sealing member 43.

In operation fluid is admitted to outer cylinder 40 through inlet 41 and exerts a downward force on the inner cylinder 42 tending to move it downwardly along the fixed sealing member 43. For any movement of the inner cylinder 42 under the influence of a given fluid pressure admitted through inlet 41 a proportionately higher pressure will be generated in the fluid duct 46 because of the larger area of fluid application to the outer surface 42a of the inner cylinder when compared with the area of the inner surface 42b of the inner cylinder.

Thus a simple hydraulic fluid pressure amplifier is provided by the invention and is simply incorporated into the hydraulic pressure circuit supplying pressurised fluid to the bolster hydraulic piston and cylinder 5 and 6 when required at the end of the working stroke.

The rigid bolster used in prior known machines is completely dispensed with. The sensitivity of the limit switch fluid control can be varied to suit the conditions or accuracy under which the machine must operate by simply adjusting the length of lever 8 mounted on column 7.

We claim:

1. A plate bending machine comprising:

a bi-partite frame of open rectangular construction;

a roll member rotatably mounted at each end in said frame;

two hydraulic piston-cylinder members mounted relative to said frame;

a movable bolster associated with the piston-cylinder members and slidably mounted on said frame for reciprocal movement relative to said roll member in response to applied fluid pressure in said pistoncylinder members, the longitudinal axis of the frame being substantially in alignment with respective axes of the hydraulic piston-cylinder members;

abutment members extending from said bolster and toward said roll member for contacting, holding and bending a plate to be bent to conform the plate to the periphery of the roll member, one of the piston and cylinders of each of said members forming a rigid joint with the movable bolster and forming a rigid structure with the roll member and the bipartite frame.

2. A plate bending machine as claimed in claim 1 in which said hydraulic piston cylinder arrangements include hydraulic circuits and a hydraulic intensifier for use in the hydraulic pressure circuits for increasing the effective pressure of fluid in a circuit, said intensifier comprising a fixed outer cylinder member and an inner cylinder member slidably, sealingly and concentrically arranged in said outer cylinder, a fixed seal member sealingly arranged in said inner cylinder, the inner cylinder being movable relative to said seal member, the outer cylinder adapted to communicate with said fluid circuit for inflow of pressurised fluid, and the inner cylinder adapted to communicate with said fluid circuit for outflow of fluid through said seal member at a greater pressure than the inflow fluid pressure.

3. A plate bending machine including a bipartite frame of open construction, a substantially vertical roll member connecting the frame members at the top and the bottom of the roll member, hydraulic cylinderpiston members mounted relative to said frame members, a movable bolster slidably mounted and extending between said frame members for movement towards and away from said roll member in response to fluid pressure in said cylinder piston members, said roll member and bolster member constituting the sole supporting connection between the frame members, said bolster including abutment members for contacting a plate to be bent whereby the plate is conformed to the periphery of the roll member, one of the pistons and cylinders of each of said cylinder-piston members forming a rigid joint with said movable bolster, limit switches arranged relative to said frame members for controlling flow of fluid to said cylinder-piston members so that the final curvature of a bent plate is determined and ensuring parallel alignment of the bolster member and said roll member at the completion of a bending stroke.

4. The plate bending machine of claim 3 further comprising adjustable mounting means for said abutment members, whereby the distance between the centerline of the roll member and each abutment may be varied. l 

1. A plate bending machine comprising: a bi-partite frame of open rectangular construction; a roll member rotatably mounted at each end in said frame; two hydraulic piston-cylinder members mounted relative to said frame; a movable bolster associated with the piston-cylinder members and slidably mounted on said frame for reciprocal movement relative to said roll member in response to applied fluid pressure in said piston-cylinder members, the longitudinal axis of the frame being substantially in alignment with respective axes of the hydraulic piston-cylinder members; abutment members extending from said bolster and toward said roll member for contacting, holding and bending a plate to be bent to conform the plate to the periphery of the roll member, one of the piston and cylinders of each of said members forming a rigid joint with the movable bolster and forming a rigid structure with the roll member and the bipartite frame.
 2. A plate bending machine as claimed in claim 1 in which said hydraulic piston cylinder arrangements include hydraulic circuits and a hydraulic intensifier for use in the hydraulic pressure circuits for increasing the effective pressure of fluid in a circuit, said intensifier comprising a fixed outer cylinder member and an inner cylinder member slidably, sealingly and concentrically arranged in said outer cylinder, a fixed seal member sealingly arranged in said inner cylinder, the inner cylinder being movable relative to said seal member, the outer cylinder adapted to communicate with said fluid circuit for inflow of preSsurised fluid, and the inner cylinder adapted to communicate with said fluid circuit for outflow of fluid through said seal member at a greater pressure than the inflow fluid pressure.
 3. A plate bending machine including a bipartite frame of open construction, a substantially vertical roll member connecting the frame members at the top and the bottom of the roll member, hydraulic cylinder-piston members mounted relative to said frame members, a movable bolster slidably mounted and extending between said frame members for movement towards and away from said roll member in response to fluid pressure in said cylinder piston members, said roll member and bolster member constituting the sole supporting connection between the frame members, said bolster including abutment members for contacting a plate to be bent whereby the plate is conformed to the periphery of the roll member, one of the pistons and cylinders of each of said cylinder-piston members forming a rigid joint with said movable bolster, limit switches arranged relative to said frame members for controlling flow of fluid to said cylinder-piston members so that the final curvature of a bent plate is determined and ensuring parallel alignment of the bolster member and said roll member at the completion of a bending stroke.
 4. The plate bending machine of claim 3 further comprising adjustable mounting means for said abutment members, whereby the distance between the centerline of the roll member and each abutment may be varied. 